1. Field of the Invention
The present invention relates to pipe leak testing equipment, and more particularly to a pipe plug for testing piping systems for fluid integrity.
2. Description of Related Art
Piping systems are typically constructed by connecting sections of pipe with fittings, valves, and other accessories. It is customary for pipe systems to be pressure tested for leaks prior to entering service. Such tests require that the pipe system, or a section thereof, be pressurized and inspected for leaks. In addition, it is often necessary to isolate a section of pipe for various reasons. For example, maintenance matters and safety considerations often require that a particular section of pipe connected to a system be isolated from the rest of the system while work is being performed.
U.S. Pat. No. 2,607,370 to Anderson (1948), discloses a pipe plug for sealing the ends of pipes wherein a cam lever is used to radially expand a seal. U.S. Pat. No. 2,974,685 to Nooy (1961), discloses a pipe plug with a sealing arrangement combined with an expansible locking arrangement in a manner such that rotation of a wing nut generates compressive force that expands a seal while also expanding a locking mechanism. U.S. Pat. No. 3,561,490 to Little (1971) discloses a pipeline testing apparatus that relies on upstream pressure to activate an internal mechanism that plugs the pipe. U.S. Pat. No. 4,385,643 to Noe (1983), discloses a pipe plug designed wherein a plurality of jaws are independently engaged with the body for movement along the ramp surface to cause the jaws to extend and grip the inside surface of the pipe. U.S. Pat. No. 4,574,618 to Anthony et al. (1986), discloses a pipe that relies on a fluidic mechanical actuator to generate a axial compression thereby causing one or more seals to expand radially when subjected to an axial force. U.S. Pat. No. 4,760,868 to Saxon (1988), discloses a pipe plug device wherein rotation of a threaded nut creates an axial compressive force to form a seal by radial expansion of first and second fluid seals. U.S. Pat. No. 5,797,431 to Adams (1998), discloses a pipe plug wherein rotation of a threaded nut causes axial compression and radial expansion of the seal, and a helical spring assists in relaxing the seal.
While the pipe plugs disclosed in the background art have proven somewhat effective in providing devices capable of sealing a pipe there remain a number of limitations and disadvantages in the art. One such disadvantage relates to the axial compression methods and mechanisms employed to form a radially expanding seal. More particularly, requiring the user to manipulate or rotate a threaded nut to provide axial compression for the purpose of radially expanding a resilient seal is considered particularly undesirable as access to the inserted pipe plug is often difficult due to space limitations and/or the orientation of the inserted pipe plug.
Accordingly, there exists a need for an easy to install pipe test plug for temporarily isolating piping systems during testing, repair and maintenance, for bypassing of damaged lines, and for isolating piping systems during construction. More particularly, there exists a need for a pipe plug apparatus configured for insertion into a section of pipe and adapted to radially expand so as to engage the inner surface of the pipe and form a positive seal therewith. There further exists a need for such a device wherein the seal is formed without requiring the user to manually rotate a threaded nut or actuate a mechanical lever.